Universal stripping arrangement for dies



March 18, 1947.

C. L. HORNB ERGER UNIVERSAL STRIPPING ARRANGEMENT FOR DIES Filed July so, 1945 2 Sheets-Sheet 1 (9 INVENTOR.

Mardl 7- I c. L. HORNBERG'ER 2,417,414

7 UNIVERSAL STRIPPING, ARRANGEMENT FOR DIES Filed July 30, ,1945 2 Sheets-Sheet 2 INVEN-TOR,

Patented Mar. 18, 1947 UNIVERSAL STRIPPING ARRANGEMENT FOR DIES Clarence L. Hornberger, Manheim Township, Lancaster County, Pa., assignor to Armstrong Cork Company, Lanca Pennsylvania ster, Pa, a corporation of Application July 30, 1945, Serial No. 607,7 68

10 Claims.

My invention relates to dies and more particularly to an arrangement for stripping died material from within the die cavity. The invention is particularly useful in connection with the shearing or shearing and piercing of sheet metals such as aluminum parts used in aircraft fabrication.

An object of my invention is to provide a stripping arrangement which is substantially universal in its application so that dies for shearing or piercing various outlines may be conveniently inserted and removed from the die set and positive stripping obtained; thus providing for economical fabrication of short runs of material.

Another object of my invention is to provide a stripping arrangement in the die set which will apply a substantial pressure to the material to be ejected in cooperation with mechanism associated with the cavity die assembly, which mechanism may be removed from the die set as a unit with the cavity die assembly, thus making convenient the insertion and removal of cavity dies for short runs while providing for a positive stripping action.

Other objects of my invention will become apparent with a consideration of the following detailed description.

In order, that my invention may be more readily understood, I will describe the same in conjunction with the attached drawings in which:

Figure 1 is a sectional view illustrating the die set of my invention;

Fig. 2 is a top plan view of the die shoe with the cavity die and its backup plates removed in order to expose the stripping arrangement for illustration;

Figure 3 is a detailed sectional view showing one of the stripping pins in partially retracted position; and

Figure 4 is a perspective view of an article of the type which may be sheared and pierced with the die set of the present invention.

Referring first to Figure 1, the die consists essentially of a punch die assembly 2 and a cavity die assembly 3 which are adapted to be moved relatively to one another to effect a shearing or piercing operation or both upon a sheet of material disposed between the dies. The punch die assembly 2 includes a backup plate 4 to which the punch is attached by rivets 5', twobeing shown in Figure 1. The punch 2 and its backup plate 4 are unitary so that they may be readily inserted and removed from the die set; This is particularly advantageous where short runs of items are made, such as frequently occur in airplane parts fabrication.

The punch and its backup plate 4 are held in position against a so-called waffle plate 5 by means of edge clamps 6 and 1 disposed at the transverse edges of the backup plate 4. The clamps 6 and l are attached to the wafile plate 5 by hollow head cap screws 8 and 9, one being shown in each side in Figure 1, but two being generally employed on each side as indicated in Figure 2 in order to firmly secure the punch in position against the wafile plate. Locating dowel pins I it are provided for properly aligning the elements in the press. c It will be noted that the dowel pins ll! extend through the backup plate 4 and the wafil plate 5 into a punch holder or die shoe II. The waffle plate 5 is secured to the punch or die shoe holder II by hollow head cap screws [2.

The punch die assembly 2 is adapted for movement toward and away from the cavity die assembly 3 and, to provide for accurate movement, the customary guiding mechanism used in die sets may be provided. This includes cylindrical ways l5 which receive bushings l3 provided in openings [4 in the die shoe II. The bushings l3 serve to guide the die assembly in its reciprocatory movement toward and away from the cavity die 3, sliding motion being efiected on the upright ways {5. In the embodiment chosen for illustration, two ways l5 are provided, as best 48, and the auxiliary equipment is demountable as a unit in th same manner as the punch die assembly 2. Edge clamps 20 are provided for'clamping the cavity die assembly to a die shoe 2! by means of hollow head cap screws 22, and dowel pins 23 serve to align the cavity die members with respect to the die shoe 2 I. The piercing punches l9 cooperate with die openings 24 provided in the punch element 2 and serve in cooperation to pierce holes in sheet material disposed between the die elements.

A spacer plate 25 is positioned between the die shoe 2! and a bolster plate 26 and dowel pins 2'! are provided for properly aligning the spacer plate 25 and die shoe 2 I, Hollow head cap screws 23 secure the spacer plate 25 and die shoe 2! together. The whole mechanism above described including and extending above the spacer plate 25 constitutes a die set which may be removed from the operatingpunch press or in-' serted therein as a unit. When "the die set is assembled in a conventional press, cap screws 29 are provided for bolting the die set to the bolster plate 26 of the press as shown in Figure l.

The cavity die assembly 3 includes a stripper plate 3i] which is disposed within the opening in the cavity die. The plate 30 is provided to eject the sheared piece from within'the die opening, and when relatively'heavy metals are to the lower platen of the press and applies yield ing force to a piston or floater 3! which isslidable within an opening 32 in the bolster plate 26. H

The floater 3! is provided with a radial extension 33 which provides a shouldert-t for engagement with the bottom of a recess 35 counterbored in the bolster plate 26. The floater 3! carries a hardened steel plate which is of a diameter greater than'the diameter of the floater 3i and is free to-slide within a counterbore 3'! provided in the spacer plateZE and is limited in its down- Ward movement by a shoulder 38 which is formed inthe-spacerplate 25.

- Inorder to provide for universal stripping, regardless of the shape or configuration-of the piece being died at any particular time, thus making possible the use of a single stripping arrangement-for any die cavity 'assembly'which may be attached to the 'dieshoe, I provide a multiplicity of closelyspaced openings in the die shoe 2! and in each; of these there is received a stripper pin 38 which'is preferably hardened and ground to siZe.- T-hestripper pins 39 rest upon the hardened steel platetfiand certain of these pins engage stripper plate holders 4E1 whichare'secured to the stripper plate 3!! and pass through the backup plates i5 and I8 and into the die shoe 2! as shown in Figure 3 where the stripper-plate holders 4!) are illustrated in detail. The holders d6 consist of a main body ii which is shouldered at 32 and the reduced section is riveted as indicated at 43 to the'plate S9. The main body 4| passes with clearance through the backup plates I 6 and I 8 and is shouldered and provided with a screw thread which receives a hexagonal nut 44. The assembly is afiected by riveting the stripper plate holder 40 to the stripper plate 30 by the rivet 43, the main body d! being then passed through openings provided in the backup plates 16 and I8. The nut 4 is then applied and draws the stripper plate 30 into its desired final position. A resilient stripping material 55, such as a body of cork composition, may be interposed in the die cavity between the stripper plate 30 and the backup plate IE to hold the parts in the position shown in Figure '1 with the stripper plate 36 in its extended position even when the die set is removed from the press. (In- Figures 1 and-3 the floater 3| and'the hardened steel plate 36 are shown in slightly retracted position so that there may be clearly shown the disposition of'the stripper plate holders 4t and the stripper pins 39. In normal operation the arrangement will preferably be such that the stripper pins 39' will just clear the nuts dd when the floater 35 is elevated to its upper most position by the pneumatic die cushion 41.)

The die shoe 2! is counterbored as indicated at id to receive the stripper plate holders and the nuts which are associated with them. This is best shown in Figure 3.

In the operation of my die set, the die shoe ii and the waifie plate 5 are secured together by the bolts l2. The'die shoe 2E, spacer plate 25, and stripper pins 39 are also set up and the screws 29 arescrewed down to secure the assembly to the bolster plate of the press. This is a conventional die set up. An appropriate punch assembly 2 is inserted into the set, being aligned by the dowel pins it and clamped by the'edge clamps 5 and T. A corresponding cavity die assembly, including the cavity. member 3, the backup plates :6 and [8, the stripper plate and its holders 4%, together with associated mechanism is afiixed to the die shoe 2|, being aligned by dowel pins 23 and held in position by edge clamps 2d. The stripper plate holders 46 are disposed within the counterbored recesses 4'6 of the die shoe 2 l. The

pneumatic die cushion t! will then be actuated.

and elevated until it is in engagement with the bolster plate 26. This will bring the stripper. pins 32 to a position where those which engage the stripperplate holders All will lie in close proximity thereto. the die cushion so as to maintain a constant loadingjon the pins 39. A sheet of material to'be fabricated will be disposed in the opening between the punch 2 and the cavity Sand the punch and its associated mechanism will be moved toward the cavity 3, sliding alongways l5, force being applied through the die shoe. H by the ramof the punch press. As the dies close, the punch 2 will force the metal into the opening in the cavity 3 effecting a shearing of the metal into an outline corresponding to the shape of the opening in the'cavity die '3. The force appliedto the punch 2 through the sheared metal, being'greater than the die cushion loading, will. depress the stripper plate 39, and the stripper plate holders dll will engagetheir correspondin stripper pins as which will in turn apply force .to the hardened steel plate 36, the floater 3|, and the pneumatic die cushion 4?; the whole being depressed simultaneously. The piercing punches l8 will effect a piercing of the metal to provide openings therein and the punched out portions will move through the openings 24 in the punch 2 and will eventually be disposed in, the openings in the wafile plate 5 from whence they may be blown in the manner well known in the art.

As the dies are opened, the ion s! will apply force to the pins 39' through the hardened steel plate 36 and'the floater 3i and the stripper plate holders Gil willmoVethe-stripper plate to its normal position. with the nuts 44 noted that the piece thereshown has a large Air will be constantly supplied to.

pneumatic die cushperipheral area 48 and is provided with three relatively small pierced openings 49. Such a piece would be difiicult to remove with an ordinary resilient stripper arrangement.

From the foregoing description, it will be clear that with my die set and stripping arrangement, practically any shape of piece may be conveniently sheared or pierced or both, utilizing a universal stripper arrangement to remove thepiece from within the die cavity and away from the piercing punches. All that is necessary in fabricating a die for'use with my universal stripper is to predetermine the position of the stripping pins 46 so that they may be received in certain of the bores 46 provided in the die shoe. By reference to Figure 2 it will be clear that there are many bores 46 and that they are closely spaced so that it will be a very simple matter to locate the stripper plate holders in any desired location, regardless of the shape of the piece being sheared or its size, provided, of course, it falls within the limits of the size of the die set. In some dies only two stripper plate holders and corresponding pins may be utilized, whereas in others as many as six or more may be required.

It will be noted that while the counterbores 46 are relatively closely spaced, there is a substantial area of metal 58 surrounding each opening 46. This insures that the cavity die 3 will be properly supported and prevented from springing under the terrific forces encountered in the shear-- ing and piercing of thick metal sheets. This makes possible the use of thin backup plates l6 and I8 for supporting the cavity die 3 and, in fact, these may be formed of steel plate about ,41 thick. Such dies are commonly used in the aircraft industry and are desirable because they are inexpensive to manufacture and are wholly acceptable for the shearing and piercing of aluminum and similar metals.

While I have illustrated and described a preferred embodiment of my invention, it will be understood that the same may be otherwise embodied and practiced within the scope of the following claims.

I claim:

1. In a die set of the type in which a punch die assembly and a cavity die assembly are mounted for relative motion to bring the dies together to work a sheet of material disposed therebetween and in which the cavity die assembly is provided with a stripper plate for ejection of the worked sheet from within the cavity die, a universal stripping arrangement adapted for actuation of stripper plates of various shapes and sizes mounted in said die set comprising a plurality of stripping pins received within closely spaced chambers formed in a die shoe and terminating in the surface of said die shoe, substantially the entire area at said surface being formed of chambers spaced by relatively thin walls, and means for moving said pins in unison to stripping position.

2. In a die set of the type in which a punch die assembly and a cavity die assembly are mounted for relative motion to bring the dies together to work a sheet of material disposed therebetween and in which the cavity die assembly is provided with a stripper plate for ejection of the worked sheet from within the cavity die, a universal stripping arrangement adapted for actuation of stripper plates of various shapes and sizes mounted in said die set comprising a plurality of stripping pins received within closely spaced chambers formed in a die shoe and terminating in the surface of said die shoe, substantially the entire stripping area at said surface being formed by chambers spaced by relatively thin walls to support the cavity die assembly in the working area thereof, and means for yieldingly holding said stripper pins in stripping position, said means being retractable upon the application of pressure to one or more of said stripper pins.

3. In a die set of the type in which a punch die assembly and a cavity die assembly are mounted for relative motion to bring the dies together to work a sheet of material disposed therebetween and in which the cavity die assembly is provided with a stripper plate for ejection of the worked sheet from within the cavity die, a universal stripping arrangement adapted for actuation of stripper plates of various shapes and sizes mounted in said die set comprising a plurality of stripping pins received within closely spaced chambers formed in a die shoe and terminating in the surface of said die shoe, substantially the entire stripping area at said surface being formed of chambers spaced by relatively thin walls to support the cavity die assembly in the working area thereof, and an air cushion yieldingly holding said stripper pins in stripping position.

4. In a die set of the type is which a punch die assembly and a cavity die assembly are mounted for relative motion to bring the dies together to work a sheet of material disposed therebetween and in which the cavity die assembly is provided with a stripper plate for ejection of the worked sheet from within the cavity die, a universal stripping arrangement removable from the die set as a unit and adapted for actuation of stripper plates of various shapes and sizes mounted in said die set comprising, a die shoe, a spacer plate attached to the-die shoe, a plurality of stripping pins received within closely spaced chambers formed in the die shoe and terminating in the surface of said die shoe, substantially the entire stripping area at said surface being formed of chambers spaced by relatively thin walls to support the cavity die assembly in the working area thereof, a stripper pin actuating plate reciprocable within said spacer plate to mov said stripper pins in unison to stripping position, and means for limiting movement of said pin actuating plate in its reciprocatory movement.

5. In a die set of the type in which a punch die assembly and a cavity die assembly are mounted for relative motion to bring the dies together to worka sheet of material disposed therebetween and in which the cavity die is supported b a relatively thin backup plate and is provided with a stripper plate for ejection of the worked sheet from within the die cavity, a universal stripping arrangement adapted for actuation of stripper plates of various shapes and sizes which may be mounted in said die set, comprising a plurality of stripping pins received within closely spaced chambers formed in a die shoe, said chambers terminating in the surface of said die shoe which receives said backup plate, said chambers constituting a major portion of the stripping area of the die shoe and spaced by walls which are adapted to support the cavity die assembly, and means for yieldingly urging said stripper pins in unison toward said cavity die assembly engaging surface of the die shoe.

6. In a die, a die shoe, a cavity die assembly supported upon the die shoe and demountable therefrom, said assembly inculding a cavity die member, a stripper plate for said cavity die mem ber, and a plurality of stripper plate holders adapted to move the stripper plate to stripping position; a pluralitys'of' chambers in the die shoe adapted to receive the ends of said stripper plate holders, stripper'pins movable within said chambers to engage said stripper plate holders, and yielding means for applying force to said stripper pins to urge said stripper plate to stripping posi tion.

' 7. In a die, a die shoe, a plurality of closely spaced chambers formed throughout a major portion of the surface of the die shoe in the area to receive a cavity die assembly, said chambers being: adapted to receive the stripper plate holders, of said cavity die assembly, stripper pins movable Within said chambers, and means for yieldably urging said stripper pins to stripping position.

8. In a die, universal stripping arrangement comprising a die shoe, a plurality of closely spaced chambers separated by Walls of material terminating in a common plane to support a cavity' die assembly, stripper pins movable within said chambers to engage complementary stripper plate holders, and means for yieldingly urging said s ripper pins to stripping position.

9. In a die, a'universal stripping arrangement 7 comprising a die shoe, a plurality of closely spaced 7 plate through said stripper plate holders'in movemerit of said stripper plate to'stripping position, and an air cushion yieldingly urging said stripper pins into stripping position and retractable upon theapplication of force to the strippingv pins when theistripper plate is moved Within the cavity die opening.

10. In a die, a die shoe, a cavity die-assembly supported on the die shoe and demountable therefrom, said assembly including a cavity die closely spaced chambers in the die shoe adapted to receive said stripper plate holders, stripping pins movable Within said chambers to engage said stripper plate holders, and means for moving said stripper pins to stripping position.

CLARENCE L. 'HO'RNBERGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name 'Date 'Hedberg 'June 26, 1945 Lorenz Aug. 7, 1906 Weiss June 20, 1939 FOREIGN PATENTS Country Date French Mar. 24, 1928 Number 2,379,003 828,225 2,162,925

Disclaimer 7 2,417,414.0larenc Homberger," Manheim Township, Lancaster P8. UNIVERSAL STRIPPING ARRANGEMENT FOR Dms. ;Patent,,db,t dYMaru 18, Armstrdng Cork 1947. Disclaimer filed Dec. 22, 1949, by the assigned,

Company. Hereby enters this disclaimer to claim 5 of said patent.

[Oflicial Gazette January 31, 1950.] 

